Method of making a filter media with an enriched binder

ABSTRACT

Water filtration media having a charged material affixed directly to binder material used in the fabrication of the filter media. A microbiological interception enhancing agent is added to the binder directly. The media having a charged material and a microbiological interception enhancing agent both affixed directly on or in a binder material is then combined with core filter media and prepared as a filtration media. A filter is prepared from the treated filter media.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a water filtration media having acharged material affixed directly to binder material used in thefabrication of the filter media. A microbiological interceptionenhancing agent may also be added to the binder directly. In oneembodiment, the present invention relates to a method of making a filtermedia having a charged material and a microbiological interceptionenhancing agent both affixed directly on a binder material. Theresultant enriched binder is then combined with core filter media andprepared as a filtration media.

2. Description of Related Art

Generally, carbon or activated carbon fibers or structures that form thecore filter media in a filtration system may be chemically treated withcharged material and/or any compatible microbiological interceptionenhancing agent, with or without a biologically active metal. A binderor thermoplastic material in powder, particulate, or fiber form, is thencombined to provide enhanced strength. In some instances, the activatedcarbon/binder combination is chemically treated with charged materialand compatible microbiological interception enhancing agents.

The prior art does not teach combining charged material directly to thebinder, or combining a microbiological interception capability directlyto the binder, with or without the addition of charged material.

Microbiological interception enhancing agents that comprise a cationicsilver complex are known in the art. Generally these agents aredeposited on either carbon block or fiber filters for water purificationand demonstrate excellent viral and bacterial interception. The methodfor depositing the agent in these applications has been known to berather complicated. A cationic silver complex (charged material) isgenerally formed directly on activated carbon in a two step treatmentprocess. The activated carbon is treated by cationic material and thenreacted with silver ammonia complex to form a cationicsilver-amine-halide complex. This process has been taught in part by thefollowing U.S. Pat. Nos. 6,630,016; 6,835,311; 6,953,604; 6,959,820;6,998,058; 7,008,537; 7,011,753; and 7,144,533, which were issued toKoslow, and assigned to KX Technologies LLC.

A silver ammonia complex is prepared by reacting a silver nitratesolution with sodium chloride to precipitate silver chloride. The silverchloride is washed thoroughly to remove completely nitrate ions. Theconcentration of nitrate ions is monitored during the rinse. A largeamount of ammonia solution is then used to dissolve the silver chlorideto form a silver ammonia complex solution. The activated carbon is thentreated and dried at approximately 300° F. for a period of time,typically overnight.

The present invention deviates from this known process insomuch as thecharged material or the microbiological interception enhancing agents,or both, are added directly to the binder material that provides thestructural integrity for the activated carbon.

SUMMARY OF THE INVENTION

Bearing in mind the problems and deficiencies of the prior art, it istherefore an object of the present invention to provide a more efficientchemistry for microbiological interception within a filter media.

It is another object of the present invention to provide method ofcombining charged material directly to binder material prior tocombining the binder material with the core filter media material in afilter media fabrication process.

It is another object of the present invention to provide a method ofcombining microbiological interception enhancing agents directly tobinder material in a filter media fabrication process.

It is yet another object of the present invention to simplify theprocess of incorporating microbiological interception enhancing agentswithin the core filter media, as well as simplifying the chemistry ofthe process, by adding the microbiological interception enhancing agentdirectly to the binder material or to binder material having chargedmaterial attached thereto, and by decreasing the amount of sodiumbromide and charged material that would have otherwise been combineddirectly within the filter core media itself, and further eliminatingthe use of sodium chloride and ammonia.

It is another object of the present invention to enhance themicrobiological interception of carbon block filters over the prior artby adding charged material to the binder material and combining thecharged material with microbiological interception enhancing agents onthe binder, so as to no longer reduce the available surface area on theactivated carbon.

A further object of the invention is to provide a method forincorporating microbiological interception to carbon filters whichaccommodates a greater variety of activated carbon mesh sizes.

It is yet another object of the present invention to provide a method ofusing a binder material to control the distribution of charged materialand microbiological interception enhancing agents within a carbon blockfilter media.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specification.

The above and other objects, which will be apparent to those skilled inthe art, are achieved in the present invention which, in a first aspect,is directed to a method of making a filter media having amicrobiological interception capability, comprising: combining a chargedmaterial directly to a binder material, forming a charged bindermaterial; combining a core filter media with the charged bindermaterial; and forming a filter media with the combined core filter mediaand the charged binder material. The step of forming the filter mediamay include extruding or compression molding the combined core filtermedia and charged binder into a solid composite or block. The chargedmaterial may include: a colloid; a small charged molecule; or a linearor branched polymer having positively charged atoms along the length ofthe polymer chain having a counter ion associated therewith. Morespecifically, the charged material may include a solution of sodiumbromide and a homopolymer of diallyl dimethyl ammonium chloride orpoly-DADMAC.

In a second aspect, the present invention is directed to a method ofmaking a filter media having a microbiological interception capability,comprising: combining a charged material, a microbiological interceptionenhancing agent, and a binder material to form an enriched binder; andcombining a core filter media with the enriched binder; and forming thefilter media with the core filter media and the enriched binder. Themicrobiological interception enhancing agent may comprise a biologicallyactive metal salt solution including biologically active metals. Silverbromide may be added directly to the charged binder.

In a third aspect, the present invention is directed to a method ofmaking a filter media having a microbiological interception capability,comprising: combining a binder material with polyacrylic acid (PAA), thePAA in 35% aqueous solution in an amount approximately 0.1% to 10% byweight of the binder material to form a binder-PAA combination; dilutingthe binder-PAA combination in deionized water in an amount at 18% to 72%by weight of the binder material; drying the binder-PAA combination, andcrushing into a powder; mixing approximately 1% to 5% of the chargedmaterial as a percentage of the binder material weight with AgBr at anamount approximately 0.05% to 0.5% by weight of the core filter media;mixing deionized water with the charged material and the AgBr at anamount 18% to 54% by weight of the binder-PAA combination to form acharged material-AgBr solution; combining the charged material-AgBrsolution with the binder-PAA combination and drying resultantcombination to form an enriched binder; combining a core filter mediawith the enriched binder; and forming the filter media with the corefilter media and the enriched binder.

In a fourth aspect, the present invention is directed to a method ofmaking a filter media having a microbiological interception capability,comprising: combining a charged material, a microbiological interceptionenhancing agent, and a binder material to form an enriched binder,including: combining the binder material with polyacrylic acid (PAA),the PAA in 35% aqueous solution in an amount approximately 0.1% to 10%by weight of the binder material; diluting the PAA and binder materialcombination in deionized water in an amount at 18% to 72% by weight ofthe binder material to form a binder-PAA combination; combining thecharged material in an amount approximately 1% to 5% by weight of bindermaterial, and AgBr in an amount approximately 0.05% to 0.5% by weight ofthe core filter media; mixing the charged material, the AgBr, and thebinder-PAA combination into deionized water at an amount 18% to 54% byweight of the binder-PAA combination; drying the resultant chargedmaterial, AgBr, binder-PAA combination; combining a core filter mediawith the enriched binder; and forming the filter media with the corefilter media and the enriched binder.

In a fifth aspect, the present invention is directed to a charged bindercomprising: binder material in powder, particulate, or fiber form, incombination with a charged material including: a colloid; a smallcharged molecule; or a linear or branched polymer having positivelycharged atoms along the length of the polymer chain having a counter ionassociated therewith.

In a sixth aspect, the present invention is directed to an intermediatefilter media composition having microbiological interception capability,comprising: a charged binder including a charged material affixeddirectly to a binder material before being combined with a core filtermedia and before the application of heat; and the core filter mediacombined with the charged binder material. The intermediate filter mediamay include having the charged binder enriched by combining at least onemicrobiological interception enhancing agent to the charged binderbefore being combined with the core filter media and before theapplication of heat.

In a seventh aspect, the present invention is directed to a filterhaving microbiological interception capability, comprising: a filtermedia having a core filter media and a charged binder, wherein thecharged binder includes binder material with charged material affixeddirectly thereto before combining with the core filter media, andwherein the filter media has the charged binder dispersed throughout thecore filter media after the application of heat; a housing enclosing thefilter media; and end caps for sealing the filter media within thehousing. The filter may include having the charged binder enriched bycombining at least one microbiological interception enhancing agent tothe charged binder before being combined with the core filter media andbefore the application of heat.

The filter may also include having the filter media formed into acomposite block structure, a spiral-wound sheet, or a pleated sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the invention believed to be novel and the elementscharacteristic of the invention are set forth with particularity in theappended claims. The figures are for illustration purposes only and arenot drawn to scale. The invention itself, however, both as toorganization and method of operation, may best be understood byreference to the detailed description which follows taken in conjunctionwith the accompanying drawings in which:

FIG. 1 is an illustration of a binder material coated with chargedmaterial and a microbiological interception enhancing agent before thebinder is added to the core filter media and heated.

FIG. 2 is the binder of FIG. 1 after a melting process.

FIG. 3 is diagram showing the distribution of charged particles affixedto binder material pursuant to the present invention on various layersof carbon block and its effect on pressure drop.

FIG. 4A is an isometric view of a filter having filter media of thepresent invention formed in a composite block structure.

FIG. 4B is an isometric view of a filter having filter media of thepresent invention formed in a pleated sheet.

FIG. 4C is an isometric view of a filter having filter media of thepresent invention formed in a spiral-wound sheet.

FIG. 4D is a detail view of the filter media of FIG. 4C.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

In describing the preferred embodiment of the present invention,reference will be made herein to FIGS. 1-4 of the drawings in which likenumerals refer to like features of the invention.

In a method for making filter media of at least one embodiment of thepresent invention, a core filter media material is combined with abinder material that has been previously treated with a chargedmaterial. In one embodiment, a core filter media is combined with abinder material that has been previously treated with a charged materialand a microbiological interception enhancing agent.

The filter media generally incorporates a microporous structure thatprovides microbiological interception capability using an appropriatepore structure, charge material, chemical treatment, or a combinationthereof. The microporous structure comprises an array of activeparticles that have a specific pore structure, as well as adsorbentand/or absorbent properties. The array can be a solid composite block, amonolith, a ceramic candle, or a flat-sheet composite of bonded orimmobilized particles formed into a coherent medium, all of which mayuse a binder or supporting bonding material. These particle arrays maybe made through processes known in the art such as, for example,extrusion, molding, or slip casting. For desirable results, themicroporous material is capable of having a mean flow path on the orderof 2 microns, although having a particular mean flow path is not acondition precedent for practicing the present invention.

In the previously identified cited prior art of Koslow, incorporatedherein by reference, the chemical treatment process used to treat thesurface of the core filter media utilized a synergistic interactionbetween a charged or cationic material and a microbiologicalinterception enhancing agent, such as a biologically active metal, thatwhen combined with the core filter media provided broad-spectrumreduction of microbiological contaminants on contact. The chargeprovided by the cationic material combined with the core filter mediaaids in electro-kinetic interception of microbiological contaminants,while the tight pore structure provides a short diffusion path and,therefore, rapid diffusion kinetics of microbiological contaminants in aflowing fluid to a surface of the microporous structure.

For the implementation of at least one embodiment of the presentinvention, the core filter media is combined with binder material thathas previously been combined with charged material, microbiologicalinterception enhancing agents, or both, ultimately to form the completefilter media for use in a filtration system. FIG. 1 depicts a binder 10coated with a charged material 12 and a microbiological interceptionenhancing agent 14. These ingredients may be of multiple types, and areidentified below. It should be noted that, although not listed,materials related to the families of the materials identified may alsobe employed with the present invention, and the lists provided are notintended to be inclusive of all such material, but rather arepresentative sample of those materials and family of materials thatsatisfy the working of the present invention.

The microporous filter medium having a binder directly treated withcharged material with or without microbiological interception enhancingagents may be used as a composite block, a flat sheet, a pleated medium,or as a spiral wound medium depending upon the application and thefilter housing design. It may be used for almost any type of filtrationincluding water and air for industrial, commercial, and domesticapplications.

Core Filter Media

The core filter media utilized may comprise an array of adsorbent and/orabsorbent active particles. The active material may be in particulate,powder, or granular form, using wet-laid or dry-laid media processes,and may include, but is not limited to, activated carbon, activatedalumina, zeolites, diatomaceous earth, silicates, aluminosilicates,titanates, bone char, calcium hydroxyapatite, manganese oxides, ironoxides, magnesia, perlite, talc, polymeric particulates, clay, iodatedresins, ion exchange resins, ceramics, super absorbent polymers (SAPs),and combinations thereof. This activated material may be converted intoa solid composite by extrusion, compression molding, or other processesknown to one of skill in the art. Exemplary processes are described inU.S. Pat. Nos. 5,019,311, and 5,189,092.

Fibers may also be used as the core filter media. These fibers maycomprise organic polymeric fibers that are capable of being fibrillated.Fibrillated fibers are generally advantageous due to their exceptionallyfine dimensions and potentially low cost. Such fibrillated fibersinclude, but are not limited to, polymers such as polyamide, acrylic,acrylonitrile; liquid crystal polymers such as VECTRAN® from KurarayCo., Ltd., of Japan, and ZYLON® from Toyo Boseki Kabushiki KaishaCorporation of Japan, and the like, ion-exchange resins, engineeredresins, cellulose, rayon, ramie, wool, silk, glass, metal, ceramic,other fibrous materials, or combinations thereof, or a combination offibers with particulate media such as, but not limited to, activatedcarbon, activated alumina, zeolites, diatomaceous earth, silicates,aluminosilicates, titanates, bone char, calcium hydroxyapatite,manganese oxides, iron oxides, magnesia, perlite, talc, polymericparticulates, clay, iodated resins, ion exchange resins, ceramics, superabsorbent polymers (SAPs), and combinations thereof. Combinations oforganic and inorganic fibers and/or whiskers, whether fibrillated ornot, are contemplated and within the scope of the invention. Forexample, glass, ceramic, metal fibers, or polymeric fibers may be usedseparately or together. In one embodiment, fibrillated lyocell fibers,such as LYOCELL BY LENZING® from Lenzing Aktiengesellschaft Corporationof Austria, are employed due to their exceptionally fine dimensions andpotentially low cost.

The core filter media may also be in the form of a flat sheet media,potentially made from fibers, or combinations of fibers and particulatemedia, which may ultimately be rolled, layered, and/or pleated forenhanced filtering applications.

Binder Material

It is well known in the art that the addition of thermoplastic orthermoset materials in powder, particulate, or fiber form, will assistin binding the active particles of the core filter media. This bindermaterial may include any of following types: polyolefins, polyvinylhalides, polyvinyl esters, polyvinyl ethers, polyvinyl alcohols,polyvinyl sulfates, polyvinyl phosphates, polyvinyl amines, polyamides,polyimides, polyoxidiazoles, polytriazols, polycarbodiimides,polysulfones, polycarbonates, polyethers, polyarylene oxides,polyesters, polyarylates, phenol-formaldehyde resins,melamine-formaldehyde resins, formaldehyde-ureas, ethyl-vinyl acetatecopolymers, co-polymers and block interpolymers thereof, andcombinations thereof. Variations of the above materials and other usefulpolymers include the substitution of groups such as hydroxyl, halogen,lower alkyl groups, lower alkoxy groups, monocyclic aryl groups, and thelike. Other potentially applicable materials include polymers such aspolystyrenes and acrylonitrile-styrene copolymers, styrene-butadienecopolymers, and other non-crystalline or amorphous polymers andstructures.

A more detailed list of binder materials that may be useful includeend-capped polyacetals, such as poly(oxymethylene) or polyformaldehyde,poly(trichloroacetaldehyde), poly(n-valeraldehyde), poly(acetaldehyde),and poly(propionaldehyde); acrylic polymers, such as polyacrylamide,poly(acrylic acid), poly(methacrylic acid), poly(ethyl acrylate), andpoly(methyl methacrylate); fluorocarbon polymers, such aspoly(tetrafluoroethylene), perfluorinated ethylene-propylene copolymers,ethylene-tetrafluoroethylene copolymers, poly(chlorotrifluoroethylene),ethylene-chlorotrifluoroethylene copolymers, poly(vinylidene fluoride),and poly(vinyl fluoride); polyamides, such as poly(6-aminocaproic acid)or poly(e-caprolactam), poly(hexamethylene adipamide),poly(hexamethylene sebacamide), and poly(11-aminoundecanoic acid);polyaramides, such as poly(imino-1,3-phenyleneiminoisophthaloyl) orpoly(m-phenylene isophthalamide); parylenes, such as poly-2-xylylene,and poly(chloro-1-xylylene); polyaryl ethers, such aspoly(oxy-2,6-dimethyl-1,4-phenylene) or poly(p-phenylene oxide);polyaryl sulfones, such aspoly(oxy-1,4-phenylenesulfonyl-1,4-phenyleneoxy-1,4-phenyl-eneisopropylidene-1,4-phenylene),andpoly(sulfonyl-1,4-phenylene-oxy-1,4-phenylenesulfonyl-4,4′-biphenylene);polycarbonates, such as poly-(bisphenol A) orpoly(carbonyldioxy-1,4-phenyleneisopropylidene-1,4-phenylene);polyesters, such as poly(ethylene terephthalate), poly(tetramethyleneterephthalate), and poly(cyclohexyl-ene-1,4-dimethylene terephthalate)or poly(oxymethylene-1,4-cyclohexylenemethyleneoxyterephthaloyl);polyaryl sulfides, such as poly(p-phenylene sulfide) orpoly(thio-1,4-phenylene); polyimides, such aspoly(pyromellitimido-1,4-phenylene); polyolefins, such as polyethylene,polypropylene, poly(1-butene), poly(2-butene), poly(1-pentene),poly(2-pentene), poly(3-methyl-1-pentene), and poly(4-methyl-1-pentene);vinyl polymers, such as poly(vinyl acetate), poly(vinylidene chloride),and poly(vinyl chloride); diene polymers, such as1,2-poly-1,3-butadiene, 1,4-poly-1,3-butadiene, polyisoprene, andpolychloroprene; polystyrenes; and copolymers of the foregoing, such asacrylonitrilebutadiene-styrene (ABS) copolymers.

Polyolefin based materials are advantageous. For example, certain typesof treated polyethylene or polyester fibers, when properly treated, areoptimal, and have the additional benefit of not significantlyinterfering with the hydrophilic nature of the resulting filter mediawhen used in modest volumes.

Polyolefin powders, such as MICROTHENE® F of Equistar Chemicals, LP ofHouston, Tex., and the like, may be successfully employed. These powderscomprise ultra-fine, spherically shaped particles with narrow sizedistribution suitable for use in a broad range of specialtyapplications. Polyolefin powders combine the unique properties of apolyolefin resin with a microfine particle size. Polyolefin powders aretypically added to certain thermoplastic and thermosetting resins toimprove surface appearance, dimensional stability, extrudability, orshrinkage characteristics. Generally, by adding one percent to sixpercent by weight polyolefin powder, resin filler distribution, moldflow, and moisture resistance, are improved while strength propertiesare successfully retained.

The binder material may be present in a carbon block filter media in anamount of about 10% to 40% by weight, more specifically about 15% to25%, and most specifically about 18%. For a binder material present inflat sheet media, a potential amount is 5% to 30% by weight, and morespecifically 8% to 15%, and most specifically 10%. It is desirable forthe binder material to have a softening point that is significantlylower than a softening point of the core filter media so that the corefilter media/binder combination can be heated to activate the bindermaterial, while the microporous structure does not melt and thereby loseporosity.

Charged or Cationic Material for Enriching a Binder

Charged molecules useful for this application may be small moleculeswith a single charged unit and capable of being attached to the binder,and after heat processing, to at least a portion of the microporousstructure. The cationic material may have one or more counter ionsassociated therewith which, when exposed to a biologically active metalsalt solution, cause preferential precipitation of the metal inproximity to the cationic surface to form a cationic metal precipitate.

The charged or cationic material may be a colloid, a small chargedmolecule, or a linear or branched polymer having positively chargedatoms along the length of the polymer chain having a counter ionassociated therewith.

If the cationic material is a polymer, the charge density may be greaterthan about 1 charged atom per about every 20 Angstroms, specificallygreater than about 1 charged atom per about every 12 Angstroms, and morespecifically greater than about 1 charged atom per about every 10Angstroms of molecular length. The higher the charge density on thecationic material, the higher the concentration of the counter ionassociated therewith. A high concentration of an appropriate counter ioncan be used to drive the precipitation of a cationic metal complex. Thecationic material consistently provides a highly positively chargedsurface to the microporous structure as determined by a streaming orzeta potential analyzer, whether in a high or low pH environment. Zetaor streaming potentials of the microporous structure after treatmentwith a high molecular weight charged polymer are generally greater thanabout +10 millivolts, and often up to about +23 millivolts at asubstantially neutral pH.

The cationic material generally suitable for use includes, but is notlimited to, quaternized amines, quaternized amides, quaternary ammoniumsalts, quaternized imides, benzalkonium compounds, biguanides, cationicaminosilicon compounds, cationic cellulose derivatives, cationicstarches, quaternized polyglycol amine condensates, quaternized collagenpolypeptides, cationic chitin derivatives, cationic guar gum, colloidssuch as cationic melamine-formaldehyde acid colloids, inorganic treatedsilica colloids, polyamide-epichlorohydrin resin, cationic acrylamides,polymers and copolymers thereof, combinations thereof, and the like.

Exemplary amines may be pyrroles, epichlorohydrin derived amines,polymers thereof, and the like. Exemplary amides may be those polyamidesdisclosed by Hou, et al., in “Microorganism Filter and Method forRemoving Microorganism from Water” (International Patent Application No.WO 01/07090), and the like. Exemplary of quaternary ammonium salts maybe homopolymers of diallyl dimethyl ammonium halide, epichlorohydrinderived polyquaternary amine polymers, quaternary ammonium salts derivedfrom diamines and dihalides, polyhexamethylenedimethylammonium bromide,and the like, such as those disclosed in U.S. Pat. Nos. 2,261,002;2,271,378; 2,388,614; and 2,454,547, all of which are incorporated byreference, and in International Patent Application No. WO 97/23594, alsoincorporated by reference. The cationic material may be chemicallybonded, adsorbed, or crosslinked to itself or to the fiber or membrane.

The cationic or charged material may include a solution of sodiumbromide and a homopolymer of diallyl dimethyl ammonium chloride orpoly-DADMAC (PDADMAC). PDADMAC is a high-molar-mass, cationic polymer,which can be used in fixation of anionic substances. It is a cationicpolymer that can be completely dissolved in water. The polymer bodycontains a strong cationic group radical and an activated-adsorbentgroup radical which can destabilize and flocculate the suspended solidsand the negative-charged water soluble matters in waste water throughelectro-neutralization and bridging adsorption. It is very effective inflocculating, decoloring, killing algae, and removing organics. It isadaptable to wide range of pH value, between 0.5 and 1.4. One PDADMACfor use may be MERQUAT® from the Naclo Company of Naperville, Ill.

Other materials suitable for use as the charged or cationic materialinclude BIOSHIELD® available from BioShield Technologies, Inc., ofNorcross, Ga. BIOSHIELD® is an organosilane product includingapproximately 5% by weight octadecylaminodimethyltrimethoxysilylpropylammonium chloride and less than 3% chloropropyltrimethoxysilane. Anothermaterial that may be used is SURFACINE® available from SurfacineDevelopment Company LLC, of Tyngsboro, Mass. SURFACINE® comprises athree-dimensional polymeric network obtained by reactingpoly(hexamethylenebiguanide) (PHMB) with4,4′-methlyene-bis-N,N-diglycidylaniline (MBGDA), and a crosslinkingagent, to covalently bond the PHMB to a polymeric surface. Silver, inthe form of silver iodide, may be introduced into the network, and istrapped as submicron-sized particles. The combination is an effectivebiocide, which may be used. Depending upon the fiber and membranematerial, the MBGDA may or may not crosslink the PHMB to the fiber orthe membrane.

Microbiological Interception Enhancing Agents for Binder Enrichment

Pursuant to at least one embodiment of the present invention, thecationic material is affixed directly to the binder. The cationicmaterial may further be exposed to a microbiological interceptionenhancing agent, such as a biologically active metal salt solution. Forthis purpose, the metals that are biologically active are well suitedfor this application. Such biologically active metals include, but arenot limited to, silver, copper, zinc, cadmium, mercury, antimony, gold,aluminum, platinum, palladium, and combinations thereof. Specifically,silver and copper are desirable. The biologically active metal saltsolution may be selected such that the metal and the counter ion of thecationic material are substantially insoluble in an aqueous environmentto drive precipitation of the cationic metal complex.

As previously stated, a particularly useful charged material,microbiological interception enhancing agent combination is a cationicsilver-amine-halide complex. The cationic amine may be a homopolymer ofdiallyl dimethyl ammonium halide having a molecular weight of about400,000 Daltons, or other quaternary ammonium salts having a similarcharge density and molecular weight. The chloride counter ion may bereplaced with a bromide or iodide counter ion. In one embodiment, theprocess includes mixing the silver bromide and charged material, such asPDADMAC, directly instead of using silver nitrate and precipitatingsilver bromide.

When used in the context of a gravity-flow water filtration system, themicrobiological interception enhanced filter media may be made withhydrophilic materials or treated with a wetting agent to provide good,spontaneous wettability. Alternatively, in other applications, themicrobiological interception enhanced filter media may be treated toprovide either a hydrophilic or hydrophobic characteristic as needed.

A Method of Charging the Binder Material

In a first embodiment, prior to combining with the core filter media,the binder material of the type identified above is combined withcharged material of the type identified above, for example, cationicmaterial from the polyolefin family. This embodiment may have an inertamount of core filter media in the binder-charged material combination;however, any inert amount of core filter media would be of an amountthat has an insubstantial effect on the binder properties or chargedmaterial properties, and would be in an insufficient amount to form thefiltration media. Methods of applying cationic material are known in theart and include, but are not limited to, spray, dip, or submergencecoating to cause adsorption, chemical reaction, or crosslinking of thecationic material to the binder material. The resultant combination isthen dried. Different types of drying processes known in the art may beemployed. The method of drying may be sprayed drying; however, thedrying process is not limited to any particular type of drying method.The drying process may be performed at a temperature range ofapproximately 150° F. to 160° F., although depending upon the dryingprocess, other temperature ranges may be more suitable, and would beconsidered acceptable. The binder materials may also containflow-enhancing agents for processing and handling.

The charged material is generally a molecule relatively long in length(on the scale of micrometers), such as those identified in thepolyolefin family of charged materials. The cationic material/binderratio may be kept below 0.5, and more specifically below 0.05. Afterheat processing, some segments of the cationic molecules are affixeddirectly to the binder by embedding in the melting binder and anchoringon the surface of the binder. In order to anchor the charged material tothe binder more securely, poly acrylic acid (PAA) is introduced to forminsoluble polyelectrolyte complexes with the cationic material.Implementation of this method provides for lower material and laborcost, enhanced performance of carbon blocks, and a safer workingenvironment. The charged binder is then combined with the activatedmaterial of the core filter media.

In another embodiment, the resultant binder and charged material, ascombined above, is further combined and enriched with a microbiologicalinterception enhancing agent. It is also acceptable to combine themicrobiological interception enhancing agent with the charged materialfirst, and then combine the resultant enrichment to the binder. Thefully enriched binder comprising a combination of binder material,charged material, and microbiological interception enhancing agent, isthen combined with the active carbon particles of the core filter media.

As an example, a microbiological interception enhancing agent of silverbromide is added directly to the resultant binder/charged materialcombination. In at least one embodiment of the present invention, thesilver bromide that is added directly to the resultant charged bindermaterial combination may be used in either wet or dried form. Theenriched binder is then added to the active particle core filter media.Heat is then applied. FIG. 2 depicts binder 10 enriched with chargedmaterial 12 and a microbiological interception enhancing agent 14 afterheat has been applied to the enriched combination. Before melting,charged material 12 and microbiological interception enhancing agent 14are affixed directly on binder 10 mainly through electrostatic forces.After melting, charged material 12 and microbiological interceptionenhancing agent 14 are attached, anchored, embedded, surrounded insideor outside binder 10, or any combination thereof. As an illustrativeexample, if an extruded carbon block is the desired result, theapplication of heat is performed during the extrusion process in whichthe enriched binder melts and disperses throughout the entire block.Concurrent with the melting of the binder material, the charged materialon the binder is simultaneously dispersed and moved along with thebinder. Due to the large particle size of microbiological interceptionenhancing agent (silver bromide), on the scale of one micrometer, andthe flocculent attribute of the charged material, the binder material,charged material, and microbiological interception enhancing agent aresecurely held within the carbon block.

The method according to at least one embodiment of the present inventionwas implemented on carbon blocks and compared with control units, carbonblock produced by a prior art method, such as the original formulationand methodology as taught by Koslow in the above-cited prior art U.S.patents. The control units have charged materials and microbiologicalinterception enhancing agents both affixed directly and initially on thecore filter media. In contrast, in at least one embodiment of thepresent invention, the charged material and microbiological interceptionenhancing agents are affixed initially and directly to the binder, andthe enriched binder is then combined with the core filter media.Although carbon blocks and activated carbon material represent thematerial of choice, the present method is not restricted to only thesematerials and may be employed with other filter materials and otherforms of the same material that similarly utilize chemical adsorptionand provide a large section of surface area to allow contaminants themost possible exposure to the filter media, such as flat sheet filtermedia. At least one embodiment of the present invention is equallyapplicable to activated media in powder, particulate, and fiber form,and also equally applicable for binder material in powder, particulate,and fiber form.

Exemplary formulations are given below.

Formulation I

In one embodiment of the present invention, the binder is treated withcharged material to form a composite. The charged binder is then addedto the core filter media. The core filter media may be either a carbonblock made from granulated or powdered activated carbon, or a flat sheetcomposite typically made from fibers.

The amount of charged material that is to be added to the bindermaterial is calculated based on the type and amount of core filtermedia, e.g., activated carbon granules or flat sheet media, requiringtreatment. The charge material may be from the polyolefin family, andmore specifically a PDADMAC; however, the present invention is notlimited to a particular charged material, and any of the chargedmaterial identified from the list above will work successfully withminor alteration to the quantities as can be determined by persons ofordinary skill in the art.

When the core filter media is a carbon block, charged material preparedin approximately a 40% aqueous solution is used to charge the binder inan amount 1% to 4% by weight of the core filter media, and specificallycharged material at approximately 3% by weight of the core filter mediais used. For charged material in its pure state, approximately 0.2% to2% by weight of the core filter media is used to charge the binder, andspecifically charged material at approximately 1% by weight of the corefilter media.

The charged material in an aqueous solution is dissolved in deionized(DI) water in an amount of at least 4% by weight of the core filtermedia, and as an illustrative example, in an amount approximately 16%.The solution is then mixed with binder material approximately 15% to 40%by weight of the core filter media, and specifically approximately 23%by weight of the core filter media. The charged binder is dried atapproximately 150° F. to 160° F. and then mixed with amorphous silicondioxide at approximately 0.05% to 3% by weight of the core filter media,and specifically approximately 0.09% to 0.5% by weight of the corefilter media, and then placed through a sieve.

For core filter media in flat sheet form, with charged material preparedin approximately a 40% aqueous solution, charge material in an amountapproximately 2% to 35% by weight of the core filter media is used tocharge the binder, and more specifically charged material atapproximately 28% by weight of the core filter media is used. Forcharged material in its pure state, approximately 1.0% to 15% by weightof the core filter media in flat sheet form is used to charge thebinder, and more specifically charged material at approximately 1% byweight of the core filter media.

For flat sheet media, the charged material in an aqueous solution isdissolved to between 3% and 30% by weight solution, and morespecifically 25% solution with DI water. The solution is then treatedonto the fiber at between 30-70% of the total weight of the bindermaterial to be treated. The charged binder is dried at approximately150° F. to 160° F. The binder fiber is then combined with the corefilter media in a typical manner to produce the flat sheet media.

Formulation II

In another embodiment of the present invention, the binder is treatedwith charged material to form a composite, and the composite is thenenriched with a microbiological interception enhancing agent.

In a similar manner to Formulation I, the amount of charged materialthat is to be added to the binder material is calculated based on thetype and amount of core filter media requiring treatment. The chargematerial may be from the polyolefin family, and more specifically aPDADMAC; however, the present invention is not limited to a particularcharged material, and any of the charged material identified from thelist above will work successfully with minor alteration to thequantities as can be determined by persons of ordinary skill in the art.

For core filter media in a carbon block state, the charged material isprepared as delineated above, in approximately a 40% aqueous solution,where approximately 1% to 4% of charged material by weight of the corefilter media is used to charge the binder, and more specifically chargedmaterial at approximately 3% by weight of the core filter media is usedto charge the binder. For charged material in its pure state,approximately 0.2% to 2% by weight of the core filter media is used tocharge the binder, and more specifically charged material atapproximately 1% by weight of the core filter media.

The charged material in an aqueous solution is dissolved in deionized(DI) water in an amount of at least 4% by weight of the core filtermedia, and as an illustrative example, in an amount approximately 16%.The solution is then mixed with binder material approximately 15% to 40%by weight of the core filter media, and more specifically approximately23% by weight of the core filter media. The binder is dried atapproximately 150° F. to 160° F. and then mixed with amorphous silicondioxide 0.05% to 3% by weight of the core filter media, and morespecifically approximately 0.09% to 0.5% by weight of the core filtermedia, and then placed through a sieve.

For the addition of a microbiological interception enhancing agent tothe charged binder, one method is to prepare a preparation of silverbromide powder (AgBr) from a silver nitrate solution of approximately1.72% and a sodium bromide (NaBr) solution. The 1.72% silver nitratesolution is prepared by dissolving 34.4 g of silver nitrate in 2000 mlreverse osmosis deionized (RO/DI) water. Sodium bromide solution isprepared by dissolving 100 g of NaBr in 2000 ml of RO/DI water. Thesilver nitrate and the sodium bromide are combined in a container toform a yellowish precipitant, silver bromide (AgBr). The supernatant isdecanted and the container is then refilled with purified water anddecanted multiple times, more specifically at least three times, inorder to remove substantially all of the sodium nitrate (NaNO3) from theAgBr. The AgBr is then dried at a temperature of 80° C. The dried AgBris then ground or pulverized. The amount of silver bromide is determinedbased on the desirability of having at least 0.1% to 1% AgBr by weightof the core filter media will ultimately be disposed within the corefilter media when the core filter media is combined with the enrichedbinder, and more specifically approximately 0.4% AgBr by weight of thecore filter media. The dried AgBr is combined with the charged binderand the resultant enriched combination is mixed with the core filtermedia and heat treated.

In one embodiment, the silver bromide is mixed directly to the chargedmaterial instead of using silver nitrate and precipitating silverbromide.

As an illustrative example, extruded carbon blocks are infused withenriched binders. The carbon blocks are prepared according to theformulation of 10% to 25% charged binder, and more specifically 15% to20% charged binder, and specifically 20% charged binder, 0% to 10%magnesium hydroxide, and more specifically 3% to 7% magnesium hydroxide,and 50% to 90% activated carbon, and more specifically 75% to 85%activated carbon. The activated carbon may be in the form of carbonpowder. Silver bromide powder is dispersed in dried form to enrich thebinder. The blocks are extruded while heat is applied to melt the fullyenriched binder.

Carbon Blocks Prepared Via Formulation II:

Three blocks were tested for short term performance passing the MS-2 andE. coli tests as shown in Table IA.

TABLE IA Short-term Microbiological Test of Carbon Block with FullyEnriched Binder End Total Flow End MS2 MS2 E. Coli E. Coli E. ColiFilter # gals Rate ΔP MS2 Inf Eff LRV inf Eff LRV 1 500 0.45 47.507.00E+05 0.0 5.9 2.90E+08 0.00E+00 8.5 2 468 0.45 47.10 7.00E+05 0.0 5.92.90E+08 0.00E+00 8.5 3 483 0.49 33.30 7.00E+05 0.0 5.9 2.90E+081.00E+02 6.5

As depicted in Table IB, a side-by-side comparison with a control waterfilter representative of the prior art formulation was conducted at aflow rate of 0.5 gpm. The control filter has charged materials with anamount of approximately 4% by weight of core filter media andmicrobiological interception enhancing agents, e.g. silver bromide, withan amount of 0.4% by weight of core filter media, both affixed directlyand initially to the core filter media. In contrast, the test articlesof this embodiment are constructed with the charged material andmicrobiological interception enhancing agents affixed to the binder, andthe enriched binder is then combined with the core filter media.

TABLE IB Long Term Microbiological Test of Carbon Block Prepared viaFormulation II at a Flow Rate of 0.5 gpm: In- Avg Daily fluent EffluentFlow End Run Challenge Total LRV LRV pH pH Rate ΔP Gals Gals Gals MS2 E.coli 6.4 7.3 0.55 24.3 60.7 1.1 61.8 6.0 9.3 6.5 8.6 0.54 25.0 53.2 1.2116.2 6.0 9.3 6.4 9.1 0.52 25.8 51.5 1.1 168.8 5.5 9.0 6.3 7.3 0.51 27.350.5 1.2 220.5 5.8 9.2 6.4 7.3 0.48 32.4 46.9 1.1 268.5 5.4 8.8 6.3 6.90.45 32.6 44.2 1.2 313.9 5.3 7.4 6.2 8.2 0.52 42.7 50.9 1.1 365.9 5.99.1 6.1 7.0 0.48 43.3 47.3 1.1 414.3 5.0 7.8 6.4 7.3 0.48 42.8 47.8 1.1463.2 5.9 9.2 6.4 8.8 0.50 42.5 49.2 1.1 513.5 6.0 9.1 6.4 7.1 0.47 43.346.6 1.1 561.2 5.5 9.1 6.2 8.1 0.50 44.0 48.8 1.2 611.2 5.4 9.2 6.3 6.60.39 45.9 38.5 2.3 652.0 6.1 9.3 5.8 7.0 0.35 50.1 34.6 1.1 687.7 6.09.0 5.9 6.7 0.27 50.9 27.0 1.0 715.7 5.9 9.3 5.9 6.9 0.04 52.4 4.4 1.0721.1 6.0 9.0

The performance of side-by-side control filters is shown in Table IC.The carbon blocks performed with substantially the same efficacy as thecontrol filters but at an enhanced flow rate as measured by totalgallons filtered. This result was realized even though the carbon blockof Formulation II was treated with a fully enriched binder that utilizedless charge material and less microbiological interception enhancingagent.

TABLE IC Control Filter (extruded carbon) In- Avg Daily fluent EffluentFlow End Run Challenge Total LRV LRV pH pH Rate ΔP Gals Gals Gals MS2 E.coli 6.4 8.6 0.54 25.2 59.3 1.1 60.4 6.0 9.3 6.5 9.3 0.51 26.2 50.9 1.2112.5 6.0 9.3 6.4 9.4 0.50 27.4 49.5 1.1 163.1 5.5 9.0 6.3 8.7 0.48 29.347.4 1.2 211.7 5.8 9.2 6.4 9.3 0.45 33.1 44.2 1.2 257.1 5.4 8.8 6.3 9.00.41 33.8 40.8 1.1 299.0 5.3 7.4 6.2 9.1 0.46 41.1 45.5 1.2 345.7 5.99.1 6.1 8.6 0.43 43.3 42.3 1.1 389.1 5.0 7.8 6.4 9.4 0.42 42.2 42.0 1.2432.3 5.9 9.2 6.4 7.2 0.42 42.2 41.7 1.2 475.2 6.0 9.1 6.4 9.2 0.41 42.639.9 1.1 516.2 5.5 9.1 6.2 9.0 0.40 43.3 39.5 1.2 556.9 5.4 9.2 6.3 9.10.35 46.4 34.8 2.1 593.8 6.1 9.3 5.8 9.2 0.31 47.5 29.9 1.2 624.9 6.09.0 5.9 9.1 0.26 49.1 25.2 1.2 651.3 5.9 9.3 5.9 9.0 0.19 45.4 18.7 1.1671.1 6.0 9.0 6.3 8.0 0.11 51.3 10.7 1.1 682.9 5.6 9.0 6.5 8.1 0.07 52.16.3 1.0 690.2 5.6 9.0

Formulation III

In another embodiment, both the amount of charged material andmicrobiological interception enhancing agent are decreased from theamounts used in Formulation II above. Additionally, the microbiologicalinterception enhancing agent in the form of silver bromide is applied ina wet form on the binder.

In the preparation of the charged binder, the amount of charged materialis decreased by approximately 10% to 50% of that utilized in FormulationII, such that in this embodiment approximately 0.05% to 2% of chargedmaterial (˜40% aqueous solution) by weight of the core filter media isused, and more specifically approximately 1% is used, or if pure chargedmaterial is considered, approximately 0.1% to 1% by weight of the corefilter media is used, more specifically 0.5%. The charge material may befrom the polyolefin family, and more specifically a PDADMAC; however,the present invention is not limited to a particular charged material,and any of the charged material identified from the list above will worksuccessfully with minor alteration to the quantities as can bedetermined by persons of ordinary skill in the art.

The charged material in an aqueous solution is dissolved in deionized(DI) water. The solution is then mixed with the wet silver bromide(AgBr). Additional deionized water is added and the combination isvigorously blended to obtain a milky solution. The solution is thenmixed with 0.5 to 2 times its weight in binder material, and morespecifically 1.3 times its weight in binder material. The resultantmixture is dried at approximately 150° F. to 160° F. The binder is mixedwith approximately 0.1% to 0.7% amorphous silicon dioxide, ground andplaced through a sieve.

Preparation of silver bromide (AgBr) powder may be prepared in a similarmanner as described above, but in smaller quantity. It originally startswith 1.72% silver nitrate solution and sodium bromide (NaBr) solution.The 1.72% silver nitrate solution is prepared by dissolving 34.4 g ofsilver nitrate in 2000 ml RO/DI water. Sodium bromide solution isprepared by dissolving 100 g of NaBr in 2000 ml of RO/DI water. Thesilver nitrate and the sodium bromide are combined in a container toform a yellowish precipitant, silver bromide (AgBr). The supernatant isdecanted and the container is then refilled with purified water andapproximately decanted three times in order to remove substantially allof the sodium nitrate (NaNO3) from the AgBr. The AgBr is then dried. Thedried AgBr is then ground or pulverized. The amount of silver bromide isdetermined based on the desirability of having at least 0.1% to 0.5%AgBr by weight of the core filter media in 40% solution will ultimatelybe disposed within the core filter media when the core filter media iscombined with the charged binder, and approximately 0.2% AgBr by weightof the core filter media is disposed. The AgBr is combined with thecharged binder and the resultant enriched combination is mixed with thecore filter media and heat treated. In this method, the amount of AgBrby weight of core filter media is decreased by approximately 60% of theFormulation II value.

Carbon Blocks Prepared Via Formulation III:

The long term microbiological test results for the carbon blocks areshown in Table II. They have a substantially lower starting pressuredrop, about 10 psi. Even after 500 gallons, the pressure drop was about16 psi.

TABLE II Long Term MB Test of Carbon Block Prepared via Formulation IIIat a Flow Rate of 0.5 gpm - Tested on an extruded carbon block In- AvgDaily fluent Effluent Flow End Run Challenge Total LRV LRV pH pH Rate ΔPGals Gals Gals MS2 E. coli 6.2 7.6 0.51 12.7 30.0 0 30.0 6.0 9.3 6.3 6.90.49 13.0 48.3 1.4 79.7 6.0 9.3 5.9 7.1 0.51 13.1 49.8 1.4 130.9 5.5 9.06.4 7.3 0.47 13.8 46.8 1.3 179.0 5.8 9.2 6.3 7.1 0.51 14.6 50.2 1.3230.5 5.4 8.8 6.3 6.5 0.47 13.6 46.3 1.6 278.4 5.3 7.4 6.4 7.0 0.52 16.251.7 1.5 331.6 5.9 9.1 6.5 7.0 0.49 15.7 48.8 1.4 381.8 5.0 7.8 6.4 7.20.46 15.1 45.2 1.5 428.5 5.9 9.0 6.3 7.0 0.48 16.2 28.6 1.4 458.2 5.96.0 6.1 6.5 0.46 16.0 45.8 1.5 505.5 5.4 9.2 6.4 7.0 0.51 18.0 50.3 1.7557.5 5.1 9.3 6.1 7.1 0.49 16.7 48.3 1.4 607.2 6.4 9.2 5.7 6.3 0.49 16.848.1 1.5 656.8 5.8 9.2 5.8 5.8 0.49 16.9 48.5 1.2 706.5 6.0 6.9 5.7 5.40.45 16.8 44.8 1.5 752.8 5.5 6.1 6.4 6.4 0.50 19.5 49.7 1.3 803.8 5.94.8 6.3 6.3 0.48 19.9 47.5 1.5 881.7 4.0 6.6

Formulation IV

In another embodiment, the formulation is the same as that ofFormulation III except for two differences: 1) a coarser activatedcarbon powder is used; and 2) the amount of charged material added tothe binder is decreased.

Preparation of the silver bromide powder is the same as delineatedabove. Preparation of the charged binder is as follows:

Once again, the charge material may be from the polyolefin family, andmore specifically a PDADMAC; however, the present invention is notlimited to a particular charged material, and any of the chargedmaterial identified from the list above will work successfully withminor alteration to the quantities as can be determined by persons ofordinary skill in the art. Charged material (˜40% aqueous solution) of0.3% to 4% by weight of the core filter media, more specifically 0.4% to0.7%, is dissolved in an amount of at least 2% DI water by weight of thecore filter media, and as an illustrative example, in 4% DI water byweight of the core filter media. The solution is then mixed with the wetsilver bromide at approximately 0.1% to 0.4% by weight of the corefilter media. At least 4% DI water by weight of the core filter media isadded, and as an example, 12% DI water by weight of the core filtermedia is added, and the combination is vigorously blended to obtain amilky solution. The solution is then mixed with approximately 15% to 40%its weight in binder material, and more specifically 23% by weight ofthe core filter media. The mixture is dried at approximately 150° F. to160° F. The binder is mixed with amorphous silicon dioxide, 0.03% to0.5% by weight of the core filter media, ground and placed through asieve.

Formulation V

This formulation is the same as the Formulation IV except polyacrylicacid (PAA) is used to facilitate the removal of microbes at lower pH,i.e., in the acidic range.

Preparation of silver bromide powder is performed in a similar manner asin Formulation IV.

In a two-step preparation, a polyacrylic acid (PAA) solution is preparedby combining a polyacrylic acid with purified water, then the PAAsolution is infused with the binder material. The PAA-binder combinationis then dried, crushed into powder, and then combined with chargedmaterial and microbiological interception enhancing agents.

In more detail, polyacrylic acid (PAA) in an amount approximately 0.1%to 10% PAA (35% aqueous solution) by weight of binder material, morespecifically 0.4% to 0.7% PAA, is diluted in DI water in an amount of atleast 2% by weight of binder material, and as an illustrative example,in an amount of 54% by weight of binder material, and mixed with thebinder material. The combination is then dried at approximately 150° F.to 160° F., and roughly crushed into powder. Approximately 1% to 5% ofcharged material as a percentage of binder material weight, and morespecifically 3% of charged material, along with 0.05% to 0.5% of theabove AgBr as a percentage of the core filter media, and morespecifically 0.15%, is then mixed into DI water, combined with the abovebinder-PAA coated powder, and dried at approximately 150° F. to 160° F.The enriched binder may then be mixed with approximately 0.1% to 0.7% byweight of binder material amorphous silicon dioxide, ground and placedthrough a sieve. The resultant is then combined with core filter media.

In a one-step preparation a polyacrylic acid solution is infused withbinder material, a charged material solution, and a microbiologicalinterception enhancing agent, to make an enriched binder mixture. Theenriched binder mixture is then dried, mixed with core filter media toproduce a filter media, and the resultant is heated.

Specifically, polyacrylic acid (PAA) in an amount approximately 0.1% to10% PAA (35% aqueous solution) by weight of binder material is dilutedin DI water in an amount at least 2% by weight of binder material, andas an illustrative example, in an amount approximately 54% by weight ofbinder material, and mixed with the binder material. Additionally,approximately 1% to 5% of charged material as a percentage of bindermaterial weight, and more specifically 3% of charged material, alongwith 0.05% to 0.5% of AgBr as a percentage of the core filter media, andmore specifically 0.15%, is then mixed into DI water, for example, in anamount 36% by weight of binder material, and combined with the above PAAcoated powder, and dried at approximately 150° F. to 160° F. Theenriched binder may then be mixed with approximately 0.1% to 0.7% byweight of binder material amorphous silicon dioxide, ground and placedthrough a sieve. The resultant product is then combined with core filtermedia, or may be sealed for future use.

Carbon Blocks Prepared Via Formulation IV & V:

As indicated by the following test results, all of the treated blockspassed the three microbiological reduction tests for virus and bacteriareduction. The data demonstrates that these filters outperformed thecontrol filters. As shown in Table III, the leaching concentration ofthe charged material in the extraction test, as determined by thetitration method, is much less than that of the control filters.

TABLE III Charged-material (Polyolefin Family - PDADMAC) Extraction Testsample ID 24 hours (ppm) 48 hours (ppm) Control filter 38.0 18.4 1 12.30.8 2 0.8 0 3 0 0 4 0 0

TABLE IV Long Term MB Test of Carbon Block Prepared via Formulation IVat a Flow Rate of 0.5 gpm - Carbon block Avg Influent Effluent Flow EndTotal LRV LRV pH pH Rate ΔP Gals MS2 E. coli 5.90 9.88 0.51 20.8 52.6.32 9.21 5.98 9.34 0.51 22.7 102 6.62 9.03 6.08 9.12 0.51 24.4 152 6.899.12 5.75 8.81 0.48 27.3 202 6.65 9.26 5.57 9.01 0.47 30.2 250 6.71 9.165.82 8.89 0.45 30.8 297 6.90 9.39 5.86 9.02 36.8 341 6.57 9.10 5.57 0.4033.4 382 7.15 9.48 5.59 9.13 0.38 44.9 421 6.80 9.26

TABLE V Long Term MB Test of Carbon Block Prepared via Formulation V ata Flow Rate of 0.5 gpm - Carbon block Avg Influent Effluent Flow EndTotal LRV LRV pH pH Rate ΔP Gals MS2 E. coli 5.74 10.07  0.52 16.8 52.805.90 8.94 5.90 9.22 0.52 18.2 105.30 6.32 9.21 5.98 9.15 0.50 21.2 156.06.62 9.03 6.08 9.15 0.48 22.8 204.4 6.89 9.12 5.75 9.36 0.47 26.2 251.46.65 9.26 5.57 9.15 0.44 28.2 296.6 6.71 9.16 5.82 9.08 0.43 31.3 340.26.90 9.39 5.86 9.07 0.41 36.1 381.9 6.57 9.10 5.57 — 0.39 37.4 422.07.15 9.48 5.58 8.95 0.36 44.3 458.5 6.80 9.26

Using the above-identified methodology, the initial pressure drop acrossa treated filter encompassing filter media is about 10 psi, which ismuch lower than the filters of the prior art. This is believed to be duein part because the charged material blocks the flow channel when it iscoated directly on the activated carbon. Since the method according toat least one embodiment of the present invention coats the chargedmaterial directly onto the binder, the activated carbon is left intactand the initial pressure drop is reduced. The rate of increase inpressure drop is also diminished. The charged material is concentratedon the binder that is distributed within the carbon. Negatively-chargedmatter such as dirt, humic acid, and bacteria are attracted to thepositively charged material instead of blocking the flow channel. Themechanism for this is shown in FIG. 3. The influent 22 passes throughcarbon filter layers 20′, 20″, 20′″ producing effluent 24. Grid 12represents the flow channel. Charged material 14, such as PDADMAC, onthe cross will capture negatively-charged matter 16. If there is toomuch charged material 14 on the first layer, a significant amount ofnegatively-charged matter 16 will be held on the first layer and blockthe flow channel very quickly, while charged material 14 and theactivated carbon on the second and third layers remain underutilized.The application of attaching charged material directly to the bindereffectively isolates the charged material's location when the chargedbinder is combined with the activated carbon. By concentrating chargedmaterial 14 on an isolated region on the first layer, somenegatively-charged matter may be adsorbed on the first layer and somewill pass and be adsorbed on the second or third layer. Therefore, theblock of the flow channel will be slower and hence the increasing of thepressure drop will be slower.

This method allows for the usage of coarser activated carbon, which alsoreduces the pressure drop of the filters.

The method of at least one embodiment of the present invention may beapplied on other substrates such as GUR binders (high molecular weightpolyethylene), inorganic fillers including silica, zeolite, and thelike.

The methods described above simplify the process of depositing amicrobiological interception agent within a core filter media. Themethods also decrease the amount of sodium bromide, silver nitrate, andcharged material, and eliminate the use of sodium chloride and ammoniain the filter making process.

Furthermore, since the ratio of carbon to binder may be on the order of4 to 1, less material handling is necessitated since the treatment ismade to the binder rather than to the activated carbon. In addition, incomparison to the prior art filters, about one-fifth to one-sixth waterneeded to be evaporated, thus saving thermal energy. Performance ofcarbon block filters is increased over the prior art since the chargedmaterial no longer reduces available surface area on the activatedcarbon. This also results in an increased flow rate and decreasedpressure drop.

The method according to at least one embodiment allows for theutilization of a greater variety of activated carbon mesh sizes. Incontrast, the prior art processes result in aggregation when applied onfine carbon, due to the high surface area of carbon and the high dryingtemperature. It is difficult to grind the aggregation back into finecarbon.

There was a reduction of the decomposition of the charged material dueto the lower drying temperature, which was on the order of 150° F. to160° F. in comparison with 300° F. of the prior art, which means theamount of charged material could be lowered. The existence of chargedmaterial, such as PDADMAC, at the interface between the binder andactivated carbon in the block will result in a higher water flux andlower pressure drop while maintaining or even exceeding the performanceof the original control formulation. Although their air values, whichare used to characterize carbon block tightness, are equivalent to thecontrol filters, their pressure drop is much lower. Four factors mightcontribute to this feature: 1) the swelling of the charged materialenlarged the flow channel; 2) the hydrophilicity of the charged materialenhanced the flow of water; 3) since the PDADMAC concentrated at certainplaces instead of throughout the block, bacteria or virus would bedragged to these places and inactivated there; and 4) during the initialflushing, some charged material and/or silver bromide will be washed outand leave their unoccupied space open.

Due to the concentrating of charged material, such as PDADMAC, itsamount could be further reduced. Moreover, due to the reduction of theamount of charged material and the drying temperature, the decompositionby-product could be decreased, which offers more flexibility forextrusion, e.g., higher temperatures. Additionally, the leaching ofcharged material can be decreased greatly, even down to, or below, thedetection limit of normal titration methods. The addition of polyacrylicacid to form a polyelectrolyte complex enables the removal of microbesat lower pH, i.e., in the acidic range.

Moreover, the enriched binder may be used as a vehicle for greatercontrol of the distribution of functional materials.

FIGS. 4A-4D depict filters having filter media containing charged orenriched binders of the present invention. FIG. 4A is an isometric viewof filter 40 having composite block filter media 42 between end caps 44.FIG. 4B depicts an isometric view of filter 46 having a filter media inthe form of a pleated filter sheet 48. Fig. C is an isometric view offilter 50 having a filter media in the form of a spiral wound sheet 52.FIG. 4D is a detail of spiral wound sheet 52 depicting individualspirals 54. In each embodiment, filter media 42, 48, and 52 arefabricated using charged or enriched binders of the present invention.

During filter media fabrication, prior to the application of heat whenthe binder is intentionally softened, there is an intermediate stagewhere the filter media comprises a charged binder, which has chargedmaterial affixed directly thereto, or an enriched binder, which hascharged material and microbiological interception enhancing agentsaffixed directly thereto, and is combined with core filter media. Thisintermediate combination is unique insomuch as at this is the instancein filter media manufacturing the charged material and microbiologicalinterception enhancing agents are not purposely affixed to the corefilter media.

After heat is applied to the intermediate filter media, the bindermaterial is softened, and the charged material and microbiologicalinterception enhancing agents are dispersed with the softened binderthroughout the core filter media. This is accomplished even though thepresent invention teaches using less charged material and lessmicrobiological interception enhancing agent material than previousfabrication processes. The filter media is then formed and assembledinto a filter, as depicted in the isometric views of FIG. 4.

While the present invention has been particularly described, inconjunction with specific embodiments, it is evident that manyalternatives, modifications and variations will be apparent to thoseskilled in the art in light of the foregoing description. It istherefore contemplated that the appended claims will embrace any suchalternatives, modifications and variations as falling within the truescope and spirit of the present invention.

Thus, having described the invention, what is claimed is:
 1. A method ofmaking filter media comprising: providing a charged material; providinga binder material; providing an anchoring agent for affixing the chargedmaterial directly to the binder material; combining together the chargedmaterial, the binder material and the anchoring agent; heating thecombined charged material, binder material and anchoring agent to form acharged binder material whereby the anchoring agent more securelyaffixes the charged material to the binder material by forming insolublepolyelectrolyte complexes with said charged material; combining a corefilter media with the charged binder material; and forming a filtermedia with the combined core filter media and the charged bindermaterial.
 2. The method of claim 1 wherein the charged material is acationic charged polymer.
 3. The method of claim 1 wherein the chargedmaterial is selected from the group consisting of quaternized amines,quaternized amides, quaternary ammonium salts, quaternized imides,benzalkonium compounds, biguanides, cationic aminosilicon compounds,cationic cellulose derivatives, cationic starches, quaternizedpolyglycol amine condensates, quaternized collagen polypeptides,cationic chitin derivatives, cationic guar gum, colloids includingcationic melamine-formaldehyde acid colloids, inorganic treated silicacolloids, polyamide-epichlorohydrin resin, cationic acrylamides,polymers, and copolymers and combinations thereof.
 4. The method ofclaim 1 wherein the charged material is a microbiological interceptionenhancing agent, said microbiological interception enhancing agentcomprises a biologically active metal salt solution includingbiologically active metals.
 5. The method of claim 4 wherein themicrobiological interception enhancing agent comprises a biologicallyactive metal salt solution including one or more biologically activemetals.
 6. The method of claim 1 wherein the charged material comprisesa combination of a cationic material and a microbiological interceptionenhancing agent.
 7. The method of claim 6 further including the steps:combining together the cationic material, the binder material, theanchoring agent and the microbiological interception enhancing agentprior to heating; heating said combination whereby the microbiologicalinterception enhancing agent and the cationic material securely affix tothe binder material via the anchoring agent to form the charged bindermaterial.
 8. The method of claim 6 further including the steps:attaching the microbiological interception enhancing agent to thecationic material to form a microbiologically enhanced cationicmaterial; combining the microbiologically enhanced cationic material,binder material, and anchoring agent prior to heating; and heating themicrobiologically enhanced cationic material, binder material, andanchoring agent to form the charged binder material that is affixed moresecurely to the binder material via the anchoring agent.
 9. The methodof claim 1 wherein the anchoring agent comprises poly acrylic acid (PAA)10. The method of claim 9 wherein the PAA is added to the combinationprior to the step of heating said combination of charged material,binder material and anchoring agent.
 11. The method of claim 1 whereinthe combined charged material, binder material and anchoring agent areheated to a temperature range of approximately 150° F. to 160° F. toaffix the charged material directly to the binder material for formingthe charged binder material.
 12. The method of claim 11 wherein theanchoring agent comprises poly acrylic acid (PAA).
 13. The method ofclaim 1 wherein during heating the binder material melts to affix thecharged material thereto by attachment to the outside of the bindermaterial while the anchoring agent forms the insoluble polyelectrolytecomplexes with the charged material to enhance the attachment of thecharged material to the binder material.
 14. The method of claim 1wherein during heating the binder material melts to affix the chargedmaterial thereto by attachment to the inside of the binder materialwhile the anchoring agent forms the insoluble polyelectrolyte complexeswith the charged material to enhance the attachment of the chargedmaterial to the binder material.
 15. The method of claim 1 whereinduring heating the binder material melts to affix the charged materialthereto by being embedded within the binder material while the anchoringagent forms the insoluble polyelectrolyte complexes with the chargedmaterial to increase the affixing of the embedded charged materialswithin the binder material.
 16. The method of claim 1 wherein duringheating the binder material melts to affix the charged material theretoby being anchored to the binder material while the anchoring agent formsthe insoluble polyelectrolyte complexes with the charged material toincrease the anchoring of the charged materials to the binder material.17. The method of claim 1 including: for charged material in an aqueoussolution, preparing said charged material in an amount approximately 1%to 35% by weight of said core filter media in approximately a 40%aqueous solution; or for charged material in its pure state, preparingsaid charged material in an amount approximately 0.2% to 15% by weightof said core filter media.
 18. The method of claim 17 including: whereinsaid charged material is in the aqueous solution, said steps includedissolving said charged material in deionized (DI); mixing said chargedmaterial with said binder material at approximately 15% to 40% by weightof the core filter media, forming said charged binder; and drying saidcharged binder.
 19. The method of claim 18 wherein the microbiologicalinterception enhancing agent comprises silver bromide added directly tothe charged binder.
 20. A method of making filter media comprising:providing a combination of a charged material, a binder material, and ananchoring agent for affixing the charged material directly to the bindermaterial; providing a microbiological interception enhancing agent ofsilver bromide; forming an enriched binder using said charged material,binder material, anchoring agent and the microbiological interceptionenhancing agent of silver bromide, whereby the anchoring agent moresecurely affixes the charged material to the binder material by forminginsoluble polyelectrolyte complexes with said charged material;combining a core filter media with said enriched binder; and forming afilter media with said core filter media and said enriched binder.